Trump has never been shy about interjecting insults during a debate, but this one — at the end of a debate and during a relatively bland answer from Hillary Clinton on entitlements — was jarring. As Clinton described her plans for Social Security, she referenced Trump's professed avoidance of taxes, which prompted the GOP nominee to lean into his microphone and interrupt, saying, "such a nasty woman."

The GOP nominee's assertion that he won't categorically agree to concede if he loses on Election Day may go down as one of the most jaw-dropping moments in presidential debate history. Trump has consistently said that the election is "rigged" against him — citing both possible voter fraud and media bias — but this assertion went even further.

"I will tell you at the time. I'll keep you in suspense," he said. The comment immediately drew condemnation from both Republican and Democratic corners, while some Trump surrogates argued that the candidate did not actually mean that he would consider rejecting the election results out of hand.

Throughout the campaign, Trump has flatly rejected the claims of rivals and fact-checkers who point out (correctly) that he supported the war in Iraq before the invasion. (Here's a full look at his history on the subject.)

During the debate, when he again denied his early support for the war, Clinton instructed viewers to simply look up his answers on the web. For the record, the first hit that comes up on a Google search of "Donald Trump Iraq" is an entry from FactCheck.org that concludes by noting that there is "no evidence" to back up Trump's claims of opposition to the war.

Sixteen months into Trump's run, and we're still arguing about this. Throughout the debate, Trump's use of the phrase "big league" — which, to many, sounds an odd adverb of "bigly" — evidently prompted viewers to turn to the internet for help. At 9:47 p.m. ET, Google tweeted that "bigly" was the top trending search on its engine.

Trump referenced the ongoing WikiLeaks release of hacked Clinton team e-mails, alluding to exchanges that show some of Clinton's own aides lamenting her decisions. "John Podesta said you have terrible instincts," he said, referring to Clinton's own campaign chair.